Recent efforts of the coatings industry directed at the problem of volatile organic emissions of organic coatings have promoted the use of vinyl or acrylate monomers as reactive diluents. Reactive diluents are described by Emmons, Chemistry of High Solids Alkyd/Reactive Diluent Coatings, Jr. Coatings Technology 55, No. 702, July 1983, and in U.S. Pat. Nos. 4,014,830; 4,097,677; 4,145,503; 4,178,425; and 4,224,202. While the reactive diluent technology provides reduced solvent emission and high solids coatings, such systems have the disadvantage of slow dry and film cure on application.
U.S. Pat. No. 4,304,883 (1981 to Hitachi) claims an unsaturated polyester resin composition prepared from dicyclopentadiene modified unsaturated alkyds (polyesters) containing allyl ethers and dissolved in a polymerizable vinyl monomer (styrene) and cured in the presence of air with organic peroxides. Polyesters prepared from unsaturated dicarboxylic acids are well known. Strazik et al in U.S. Pat. Nos. 4,280,938; 4,281,091; and 4,293,461 describe unsaturated condensates of an alkoxymethylmelamine, allylic alcohol and acrylamide useful for modifying alkyds for high solids air-drying compositions.
The present invention relates to improved air-drying alkyd, polyester or acrylic resins containing unsaturated polyester resins or urethane modified unsaturated polyester resins which function as cure modifiers and coatings prepared therefrom.